After reading an avherlad article (http://avherald.com/h?article=4157d291/0001&opt=0) about an aircraft with landing gear failure, I noticed in the picture caption that the Airport FRS had foamed the runway. I remember seeing this in films about aircraft disasters when I was younger, but how common is it?

Thanks,
A320ajm

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Quoting A320ajm (Thread starter): I noticed in the picture caption that the Airport FRS had foamed the runway. I remember seeing this in films about aircraft disasters when I was younger, but how common is it?

They tend to do it as soon as the aircraft comes to a stop. A Lear came down at Boeing Field a few years ago with their nose gear stuck sideways. They came to a smoky stop about mid-runway, at which point the Boeing Fire department turned the place into a foam party for about 100m in every direction.

First, foam is expensive. A five gallon drum is about $100 to $200 depending on the concentration (either 3% or 6%, 1% is not allowed for ARFF purposes). Note that that's the pure foam, which will yield much more than 5 gallons when mixed in with water. If I remember correctly, the Striker 1500 fire truck holds about 200 gallons of pure foam, so you're talking between about $4,000 and $8,000.

Also, it takes a long time to refill. So say that you foam one portion of the runway, but the plane doesn't land exactly there, or it skids off onto another unfoamed section. If you spent all your foam already, well now you don't have any left over for the actual crash.

This is an interesting quick read on the subject here. The FAA specifically warns against attempting to foam a runway with Aqueous Film Forming Foam (AFFF), which is the style of foam most widely used (by a very large margin, I would imagine), in ARFF trucks.

Foam also isn't traction friendly to emergency vehicles or rescuers. The slippery stuff can make it more difficult to get help to the right place. Foam can make it harder for pax evacuating an aircraft to get away from danger.

If there is an actual fire or smoking metal, tires, brakes, etc - foam is great to smother it. And knocking down the fire or parts hot enough to smoke is the first priority.